PHP函数怎样在类中定义与调用成员函数 PHP函数类成员函数的基础使用技巧

function

->

::

class

function

<?php

class MyClass {
    public $property = "Hello";

    public function myMethod() {
        return $this->property . " World!";
    }
}

// 创建类的实例
$obj = new MyClass();

// 调用成员函数
echo $obj->myMethod(); // 输出: Hello World!

?>

myMethod

MyClass

$this

$property

public

protected

private

<?php

class MyClass {
    private $privateProperty = "Secret";

    protected function protectedMethod() {
        return "This is protected.";
    }

    public function publicMethod() {
        return $this->protectedMethod(); // 可以访问 protected 方法
    }
}

$obj = new MyClass();
// echo $obj->privateProperty; // 错误：不能从外部访问 private 属性
// echo $obj->protectedMethod(); // 错误：不能从外部访问 protected 方法
echo $obj->publicMethod(); // 输出: This is protected.

?>

static

::

<?php

class MyClass {
    public static function staticMethod() {
        return "This is a static method.";
    }
}

// 直接通过类名调用静态方法
echo MyClass::staticMethod(); // 输出: This is a static method.

?>

$this

->

<?php

class MyClass {
    public function methodA() {
        return "Method A";
    }

    public function methodB() {
        return $this->methodA() . " called from Method B.";
    }
}

$obj = new MyClass();
echo $obj->methodB(); // 输出: Method A called from Method B.

?>

<?php

class MyClass {
    public function __construct() {
        echo "Object created.\n";
    }

    public function __destruct() {
        echo "Object destroyed.\n";
    }
}

$obj = new MyClass(); // 输出: Object created.
unset($obj); // 输出: Object destroyed.

?>

<?php

class ParentClass {
    public function myMethod() {
        return "Parent method";
    }
}

class ChildClass extends ParentClass {
    public function myMethod() {
        return "Child method"; // 重写父类方法
    }
}

$obj = new ChildClass();
echo $obj->myMethod(); // 输出: Child method

?>